Magnetospeed and MV

[elkaholic]

I chronoed the load with Superchrono previously and got 2880fps.
That was also in slightly warmer weather than now.
With the magnetospeed I got 2970fps, so minus the 10 feet its probably around 2955fps.
Somehow the same load has picked up 75fps.

I may have missed this but are you using the same lot of powder as when you tested it first?.....Rich

 

[FearNoWind]

There are so many areas for potential problems in the set up of the Superchrono acoustic chronograph that, while I would not dismiss the results out of hand, I'd never accept the results it provides over the MagnetoSpeed Chrono.
I'd accept the Superchrono results as an estimate but for MV I can ake to the bank without doubt, I'd always favor the MS.
One more thing. It seems every time I see a post discussing the MagnetoSpeed somebody complains about the fact that their groups print a bit higher on target with the MS bayonet attached. Of course they do; anything attached to the barrel will move where your rifle prints on target. But for heavens sake when will the shooting enthusiasts accept the fact that it's a CHRONOGRAPH ... it's not intended to also serve as a load testing sight in tool.

 

[MudRunner2005]

There are so many areas for potential problems in the set up of the Superchrono acoustic chronograph that, while I would not dismiss the results out of hand, I'd never accept the results it provides over the MagnetoSpeed Chrono.
I'd accept the Superchrono results as an estimate but for MV I can ake to the bank without doubt, I'd always favor the MS.
One more thing. It seems every time I see a post discussing the MagnetoSpeed somebody complains about the fact that their groups print a bit higher on target with the MS bayonet attached. Of course they do; anything attached to the barrel will move where your rifle prints on target. But for heavens sake when will the shooting enthusiasts accept the fact that it's a CHRONOGRAPH ... it's not intended to also serve as a load testing sight in tool.

I know all of this, and I do only use it as a chrono to verify after load development, but it would be nice to know what's going on during load development incase one goes hot, like it did with my .25-06 AI where it completely disintegrated the primer and left a perfect image of the case head on my bolt... If it was over velocity, I would have known my powder dispenser overcharged it, but if I don't have the chrono setup while shooting groups, I can't know that for sure, I can only know it was highly over pressured, but the cause is still speculation. Know what I mean?

 

[RockyMtnMT]

We use our MS during load work up to monitor MV. Once we get to the MV that is desired, we shoot a few more to get an accurate average MV. Then remove it and shoot for group. If the group is not acceptable then work on seating depth till it comes in. If that does not work then start over with diff powder etc. This method has net less bullets fired than when we did it all over the sky screen chrono. Chased way too many odd velocity readings.

Steve

 

[Len Backus]

Is it possible for a barrel to pick up 75 fps after break in?

I tell all my rifle customers to expect 50 to 75 fps increase. These are match grade barrels. No experience with factory barrels.

 

[snox801]

Sounds like they have you covered already. I will only add is that you seem to think its to fast for 338 win. May be the correct fps with cutting edge. I've experienced much higher fps with them. My .458 socom and 300 blk scream using those bullets compared to others. Just a thought. I've also got the same effect with gs customs

 

[EXPRESS]

I know that copper bullets tend to run higher velocities and lower pressures.
The CEBs in .338 cal are .0039" undersize, which must have an effect.
I've never noticed it being so pronounced.